For this study, we designed learning activities in which students applied newly acquired knowledge to solve meaningful daily life problems in their local community--a real, familiar, and relevant environment for students. For example, students learned about signs and rules in class and then applied this new knowledge to create their own rules for a location in their community (e.g., playground rules that tell visitors what is or is not allowed to do in a local playground) to make it more environmentally friendly. To facilitate this, we developed a mobile learning system equipped with a dictionary as well as textual annotation, recording, and sharing functions. This mobile learning system enables students to take pictures of objects, describe them verbally or in writing, and share their work with peers. Our goal was to study the effectiveness of learning activities supported by a mobile learning system on the cognitive learning process by examining the changes in students' cognitive processes and the distribution of students who reach a certain level of cognition before and after learning. Fifty-seven junior high school students participated in the research, and their views of the mobile learning system and interest in continuing use were also explored. Students were divided into one control (n=26) group and one experimental (n=31) group. The control group completed learning activities using a traditional approach while the experimental group used a learning system installed in tablet PCs. The effectiveness of the mobile PC system on students' cognitive processes was tested by comparing the control and experimental groups' pre-test and post-test outcomes. Changes in students' cognitive processes were measured by calculating the differences in student scores among three tasks. The distribution of students who reached a certain level of cognition was derived based on their learning performance. Students' perceptions were evaluated using a questionnaire survey. The mobile learning system kept records of how students used it. Our results show that the experimental students significantly outperformed the control students on test items related to high cognitive levels. Students made clear cognitive progress from the second topic to the third one. Most students rated the learning system highly and want to use it in the future. Finally, the results show that creating text annotations is the best indicator of learning. Based on these results, we recommend applying appropriate learning activities supported by a mobile learning system to facilitate students' cognitive processes when they are studying English as a foreign language in an authentic environment.